Method to produce a pile textile product and a textile product resulting from the same

ABSTRACT

A method for manufacturing a textile product includes the steps of providing an intermediate product formed by a backing having a front surface and a back surface, and yarns applied into the backing, the yarns extending from the front surface of the backing material, feeding the intermediate product along a body having a heated surface, the back surface being pressed against the heated surface, to at least partly melt the yarns present in the intermediate product to form the textile product, wherein the part of the back surface that is pressed against the heated surface has a relative speed with respect to the heated surface, and a device enabling applications of this method and to a floor covering incorporating such a textile product connected to a dimensionally stable carrier sheet using thermo reversible covalent interactions.

FIELD OF THE INVENTION

The present invention pertains to textile products, in particular floorcoverings, such as carpet, carpet tiles, rugs and mats, and themanufacturing thereof. In particular, the invention pertains to textileproducts in which yarns are connected to a primary backing without theneed of applying secondary backing. The invention also pertains to amethod to recycle floor coverings.

BACKGROUND OF THE INVENTION

From EP 1 598 476 a method for manufacturing a textile product is known,the method comprising providing an intermediate product (i.e. a productin a form not suitable for end use such as object covering, floorcovering, clothing etc.), comprising a backing having a front surfaceand a back surface, and yarns applied into the backing, the yarnsextending from the front surface of the backing material, and feedingthe intermediate product along a body having a heated surface, the backsurface being pressed against the said heated surface, to at leastpartly melt the yarns present in the intermediate product to form thetextile product. Thereafter, the textile product is cooled to normalroom temperature such that the molten yarn material is solidified. Withthis method the yarns are properly anchored in the backing withoutneeding a secondary backing of for example latex.

Latex based floor coverings have several disadvantages. Firstly, sincethe latex is water-based, latex coverings tend to be non-resistant tomoisture. They may allow moisture to pass through which on its turn canlead to the formation of mildew and molds. This cannot only degrade thefloor covering, but may also lead to environmental hazards such as poorair quality. As a consequence, when latex based floor coverings areplaced in an area where moisture is a concern, for example in lobbies,they may need to be frequently replaced. Secondly, because latex-basedfloor coverings use dissimilar materials for the yarns, the backing andthe adhesive, such coverings cannot be fully recycled. Carpet recyclingtechnologies have been developed but are expensive and do not allowcomplete recycling of the materials used, mainly due to the intenseembedding of the yarns and backing in the vulcanized latex. As a result,most floor coverings are simply discarded, burned or shredded. At best,shredded floor coverings are used as landfills but since vulcanizedlatex is hardly biodegradable, the shredded remains will be present formany years.

Alternatively the conventional latex is replaced by an adhesiveconsisting of synthetic polymers such as polyolefines and polyurethanes.This is for example known from US 2010/0260966, which discloses a carpettile that includes a face fabric having a top surface and a base, and adimensionally stabilized non-woven cushion material having a stabilizingmaterial incorporated therein. The non-woven cushion material isattached to the face fabric by using a synthetic polymer adhesive, inwhich adhesive the cushion material as well as the fabric are embeddedfor adequate bonding. Still, complete recycling of this known carpettile is hardly possible due to the embedding of the face fabric and thecushion material in the polymer.

Another solution proposed in the art is to use of hot melt adhesives.These adhesives are popular in conventional roll carpets since they arerelatively inexpensive, readily available and can be recycled moreeasily. Hot melt adhesives are also used in carpet tiles, as is knownfor example from WO 2007/127222. Still, given the fact that the bondingof the face fabric with the backing when using a hot melt adhesive needssubstantial embedding of the materials in this adhesive, completerecycling remains hard. Either the face fabric, the backing or both willinevitably be contaminated with substantial amounts of the adhesive.

Therefore, the method as known from EP 1 598 476 provides substantialadvantages, not only with regard to recycling but also with regard toenergy and raw material savings. However, the anchoring of the yarnsinto the backing is not strong enough for applications were the textileproduct is subjected to high mechanical loads such as in the interior ofcars, trains, planes, offices, shops etc. That is why preferably athermoplastic adhesive is applied to the back of the intermediateproduct before it is pressed against the heated surface for anchoringthe yarns.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method to manufacture atextile product that overcomes or at least mitigates the disadvantagesof the known method, and a device to enable application of this method.It is a further object of the invention to provide a floor coveringcomprising such a textile product, which floor covering is ideallysuitable for recycling when worn. Another object of the invention is toprovide a method to recycle such a floor covering.

To this end a method as described here-above and known from EP 1 598 476has been devised, wherein the part of the back surface that is pressedagainst the heated surface has a relative speed with respect to theheated surface. In the prior art method (which method is also known fromEP 1 916 330), the heated drum rotates in conjunction with theintermediate product, thus ensuring that the part of the back surfacethat is pressed against the heated surface has in essence the same speedas the said heated surface. This on its turn provides that there is no,or at least hardly any, mechanical disturbance of the placement of theyarns into the backing, in particular ensuring that the yarns are notpulled out of the backing. Indeed, in the intermediate product the yarnsare simply weaved, knitted, stitched or other wise applied into thebacking which means that they can be removed from the intermediateproduct by a light pulling force (e.g. manually). This is why in theart, the heated surface is rotated at exactly the same speed as theintermediate product that is fed in conjunction therewith.

Applicant surprisingly found that a substantially improved textileproduct can be obtained when there is a relative speed between the partof the back surface that is pressed against the heated surface and theheated surface itself. By enforcing a relative speed, i.e. a speeddifference at macroscopic level (thus being more than the inherentmicroscopic speed difference that exists when two surfaces are driven inconjunction, thus at least being a difference of 1 centimeter/min,typically above 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,18, 19, preferably over 20 cm/min) an additional mechanical force isimposed that actually spreads the molten material of the yarns.Apparently, in a situation where the yarns are being melted at the backsurface, such spreading forces do not pull the yarns out of the backing.The advantage of this spreading is not only that the anchoring is muchstronger, thereby eliminating the need for the application of anadditional adhesive, but also that the resulting back surface issubstantially smoother than a back surface obtainable with the method asknown from the art discussed here-above. This on its turn provides morefreedom in applying the textile product. It is noted that the speeddifference between the intermediate product and the heated bodytypically is in the range 10-100% (0% meaning no speed difference, 100%meaning that one surface stands still with respect to the other),preferably over 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80,85, 90 or 95%. However at a very high throughput speed of theintermediate product, a relative speed difference below 10% could besufficient. For example, at a throughput speed of the intermediateproduct of 40 m/min, an absolute speed difference of 2 m/min (5%) couldbe sufficient to impose an adequate mechanical spreading force. The samecould be true in case the molten material has a very low viscosity.

The invention also pertains to a device that enables the application ofthe new method, the device comprising a means for feeding a backinghaving yarns applied therein (the backing being typically fed from acarrier, e.g. a core on which the backing is wound). Although the devicecould be provided with any body having a heated surface which body canbe spatially controlled such that the backing is fed in contact with theheated surface at a relative speed with respect to that heated surfaceof the body, the device preferably comprises as a heated body a bladehaving an edge that can be heated above a temperature at which the yarnsmelt. The device further comprises a means for pressing the backingagainst the heated surface, in particular the edge of the heated blade,while being fed, and a means to further process the resulting textileproduct, for example by at least dimensioning the product (e.g. bycutting the product in separate lanes having a length of 20-50 meters).Although the known device using a heated drum to anchor the yarns canalso be used to apply the method according to the invention, for exampleby securing the drum such that it cannot rotate at all, or rotate at acircumferential speed lower or higher than the speed at which theintermediate product is fed, applicant found that a device having ablade for heating the intermediate product is ideally suitable forapplying the method according to the present invention. With a blade avery short contact time between the heated surface and the intermediateproduct can be achieved, which provides the opportunity to use incombination a relatively high temperature of the heated surface and highcontact pressure. This on its turn may give a better spreading result ofthe molten material and thus a better anchoring of the yarns.

The new method did provide the insight that a textile product havingyarns anchored to a backing and at the same time having a very smoothback surface (no matter how this product is made) can be ideally used tomake a fully recyclable floor covering. To this end the textile productis connected with its back surface to a dimensionally stable carriersheet, the textile product being connected to the sheet using thermoreversible covalent interactions. Applicant recognised that when atextile product is used wherein the yarns are mechanically anchored(e.g. by melting or reacting the yarns at the back surface of thetextile product to provide sound mechanical connection between the endsof the yarns), an adhesive does not need to have the function ofanchoring the yarns such as is the case with prior art latex based floorcoverings. This allows the use of a different type of bonding whendevising a floor covering which needs to be dimensionally stable. Priorart adhesive bonding is based entirely on Vanderwaals forces andfriction. Given the fact that such interactions are relatively weak, ahigh degree of embedding of the yarns in the adhesive is necessary. Inthe present invention covalent interactions are used to connect theself-supporting textile product with the backing sheet. Covalentinteractions are inherently very strong and need contact only onmolecular level. Physical embedding may be applied but is not essential,or at least not to the extent as used in prior art floor coverings. Thistype of connection that does not, or at least to a lesser extent, relyon embedding of an adhesive in the face fabric, on its turn allows theuse of a dimensionally stable, preferably also flexible, carrier sheetas a backing, for example a thin flexible sheet of an artificial ornatural material (for example polypropylene or cork). The use of aseparate self-supporting sheet, instead of a backing that is applied asa liquid coating and then hardened (vulcanized) in situ, on its turnallows to have no or hardly any contaminating adhesive to be present inthe backing (i.e. the carrier sheet), which obviates recycling of thefloor covering, in particular when using thermo reversible covalentinteractions. Recycling then merely takes heating the floor coveringuntil the textile product de-connects from the sheet, separating thetextile product from the sheet, and reusing the textile product and thesheet, for example to produce a new floor covering according to theinvention.

Definitions

Being flat: having a height substantially less than its width andlength. A flat object may be substantially two dimensional as a wholebut it may also be curved, rippled, rolled up etc.)

A backing: a substantially flat material, suitable for applying yarns toobtain a textile product with yarns that extend there from, typicallyused for manufacturing floor coverings but in embodiments applicable formanufacturing clothing, canvas for tents, household textile etc. Theapplication of the yarns may be accomplished by any method such as forexample tufting, knitting, weaving, sewing, stitching etc.

A floor covering: a textile product that can be used to cover objectssuch as floors (which term includes walls, ceilings etc.), furniture,the interior of cars, trains, boats, airplanes etc.

A blade: an elongated element, having a small width working surface(also called the edge), typically below 2 cm in width, preferably below1.0, 0.9, 0.8, 0.7, 0.6, 0.5, or 0.4 cm, further preferably between 0.01and 0.3 cm in width. A blade is typically operated while beingnon-rotating along its length-axis (as in contrast with a roller). Ablade may be connected to another element such as a drum.

Melting: to heat above a temperature wherein the material becomes atleast malleable, preferably reaching a state wherein the material canflow under mere gravitational forces (i.e. being liquid).

Self-supporting textile product a textile product of which the (majorpart of the) constituting yarns cannot be removed by simply pulling byhand. Typically, yarns tufted into a primary backing form anon-self-supporting textile product the yarns can be pulled out of theproduct by hand. Typically, after application of a secondary backingcomprising e.g. latex, the yarns are mechanically bonded into thetextile product to form a self-supporting textile product.

Dimensionally stable: having dimensions that do not noticeably changewhen being exposed to mechanical load (such as walking over it and otherload typical for floor coverings) or variations in temperature andhumidity.

Fibre-binding: a process wherein fibres (or yarns) are mechanicallylocked to a substrate, such that they cannot be removed by simplypulling by hand. Fibre-binding is also denoted as “yarn-binding” in thisspecification.

Embodiments of the Invention

In an embodiment the heated surface is an edge of a blade. In the art ofmelting yarns piled into a backing material using a heated surface,typically drums or rollers are used. A drum or roller is believed tohave several advantages: 1) a smooth mechanical impact on the vulnerabletextile product; 2) easy maintaining a constant temperature; 3) they canbe used for driving and guiding the textile product; 4) they can easilybe kept clean (using for example a doctor blade that scrapes the drum).In the art, blades are used when harsh mechanical impact is necessary:they are typically used for scraping, and act as a squeegee to gather anexcess of liquid or semi-liquid material from a surface. This istypically not wanted in a situation were material is to be melted andnot at the same time scraped off. However, applicant found that whenusing a blade, a better spreading result of the melted material can beobtained, without necessarily imposing too much mechanical impact on theintermediate product. If the same spreading result is to be obtainedwith a drum, a very high drum temperature is needed since the pressurecan hardly be increased to a level as high as in a situation were ablade is used. This inherently means that there are restrictions to thetype of material that can be applied. In particular those materials thatwould degrade at the required drum temperatures cannot be used. With ablade, lower temperatures can be used to obtain the same spreadingresult, or, due to the short contact time, at least the amount of heattransferred from the heated surface to the back surface of theintermediate product can be kept sufficiently low to avoid degrading ofthe materials used.

In an embodiment the intermediate product is fed between the blade and arotating drum facing the blade. This way an adequate local pressure onthe back surface of the intermediate product can be easily obtainedwithout running the risk of the intermediate product to tear.

In another embodiment the blade is vibrated when pressed against theback surface. Surprisingly it has been found that contamination of theblade, in particular deposits of molten yarn or other material can beprevented when the blade is vibrated. This goes against the commonknowledge that blades are typically used for scraping off liquidmaterial and inherently building up a deposit of such material on theblade. The reason for this not, or at least to a far lesser extent,happening when the blade is vibrated is not clear, but certainly iteliminates or at least lessens the need for regular cleaning of theblade. This makes the process very attractive from both a technical ascommercial point of view. In a further embodiment, the frequency ofvibrating is between 5000 and 50000 Hz, for example in the ultrasonicrange (above 20.000 Hz, typically between 30.000 and 40.000 Hz) whereinthe amplitude is for example in the micrometer range, typically between0.1 and 10 μm, for example between 1 and 5 μm. In an embodiment thedirection of vibrating is parallel to the intermediate product,transverse to the direction of transport of the product along the blade.

In yet another embodiment the blade is thermally connected to a non-flatcarrying element. A disadvantage of a blade in general is that its heatcapacity is relatively low given its more or less flat constitution.This means that it may be difficult to keep a blade at a constant hightemperature, in particular when being in constant contact with an objecthaving a lower temperature. This embodiment mitigates this problem bythermally connecting the blade to a non-flat carrying element. Such anelement inherently has (when a non-insulating material is chosen) ahigher heat capacity and thus can be used to transfer heat to the bladeto keep its temperature at the same level.

In another embodiment the back surface is preheated before being pressedagainst the heated surface of the body. By preheating the back surface(i.e. heating the surface at least above room temperature, typically upto at least 100° C., 90° C., 80° C., 70° C., 60° C., 50° C., 40° C., 30°C., 20° C., 10° C. or 5° C. below the melting temperature of the yarnmaterial), two things can be achieved. Firstly, the temperaturedifference between the blade and the textile product will be decreased,thereby possibly preventing that the blade cools too much upon contactwith the intermediate product. Although any amount of cooling could becompensated by heating, this would lead to a harder to control process.Secondly, by preheating the back surface, the to be molten material canbe brought for example in a state wherein it nearly melts, thereby moreor less guaranteeing that during the very short contact time with theblade, the required heat to actually melt the material can be put intothe intermediate product during the time in which molten material at theback surface is in contact with the blade for spreading purposes. In afurther embodiment the back surface is preheated by pressing a heatedpreheat surface against the back surface, the preheat surface preferablybeing a preheat drum or a preheat blade.

In yet another embodiment wherein the yarns extend through the backing(thus not alone extend at the face side, but also through the backsurface), at least a part of the yarns that extends out of back surfaceis melted. In this embodiment at least a part of yarns that extend outof the back surface (typically a loop of a yarn) of the backing ismelted. This may already provide for a sufficient mechanical locking ofthe yarns in the textile product. However, it is preferred that a partof the yarns that is present in the backing is at least partly melted.By melting the yarns that are actually in the backing, an even betterbonding between the yarns and the material of the backing can beaccomplished. This may lead to a better locking than for example meltingsolely a part of the yarns that extend from the back surface.

In an embodiment the backing comprises a thermoplastic material thatco-melts with the yarns. In this embodiment a true bonding between theyarns and the backing material can be accomplished since the moltenmaterial of both components is mixed and thereafter cooled down tobecome one (either at molecular, microscopic or macroscopic level).

In yet another embodiment the backing is a non woven fibrous material.Such material has been found ideally suitable to apply the presentinvention. It has been shown that this way a very smooth (flat) backsurface can be created and a very good anchoring of the yarns. This leadto a textile product having a very wide range of possible applications.

In an embodiment of the floor covering according to the invention, thecovalent interactions are formed by a thermo reversible reaction betweenreactive molecules present at the interface between the textile productand the sheet. This embodiment allows the reversion of the covalentinteractions by heating the floor covering. This greatly contributes tothe ease of recycling the floor covering, which can be understood asfollows. By reversing the reaction between the reactive molecules, theoriginal connecting structure falls apart in multiple smaller molecules.Such smaller molecules can be removed far more easily from the textileproduct and the sheet than conventional adhesives which comprise longchain molecules. It is for example possible to simply solve theresulting small molecules in a mild solvent, and afterwards recoverthese molecules from the solvent using any art-known method. Also, themolecules may be recycled together with fibrous material of the textileproduct and/or material of the carrier sheet, for example by blendingtherein. It is noted that thermo reversible covalent interactions per seare commonly known in chemistry. Examples can be found among Michaelreactions; nitroso dimerization reactions; cyclic anhydride reactions inwhich ester bonds are formed; reactions in which aliphatic ioneneformation takes place; reactions in which urethane formation takesplace; reactions in which azlactone-phenol adduct formation takes placeetc. (see J. Macromol. Sci. Rev. Macromol. Chem. C33 (3), 1993, pp.239-257).

In a further embodiment the reaction is between a first moleculecomprising a conjugated diene group and a second molecule comprising adienophile group. Such reactions between a conjugated diene and adienophile are referred to as Diels-Alder reactions. The advantage of aDiels-Alder reaction is that thermo reversibility can take place atrelatively low temperatures, which may enable to prevent physical andchemical damage to the face fabric and carrier sheet. It is noted that aconjugated diene is an acyclic hydrocarbon with a molecular structurecontaining two carbon-carbon double bonds separated by a single bond.The diene group may be part of a molecule that comprises atoms differentfrom carbon and hydrogen. A dienophile is the alkene (carbon doublebond) component of a reaction between an alkene and a diene. Thedienophile group may also be part of a molecule that comprises atomsdifferent from carbon and hydrogen.

In even a further embodiment the diene group is a furan (such asfurfuryl), anthracene, thiophene or pyrrole, and the dienophile group isa maleimide, fumarate, maleate or alkyne. These groups have proven to besuitable for application in the present invention. It is noted that thisembodiment does not exclude the use of different diene groups and/ordifferent dienophile groups in one application.

In an embodiment the molecules are bound to the textile product andsheet by non-covalent bindings. This embodiment allows easy applicationof the reactive molecules at the interface between the back of thetextile product and the carrier sheet. Also, the non-covalent connectionbetween the molecules and the textile product/carrier sheet allow easyremoval which is advantageous for recycling. However, the strength ofthe resulting connection in this embodiment depends largely on the typeof binding between the reactive molecules and the textile product andsheet respectively, and thus may be less than required for someapplications.

In a preferred embodiment therefore, the molecules are bound to thetextile product and sheet by covalent bindings. In this embodiment, thecomplete chain of interactions going from the back of the textileproduct to the top of the carrier sheet is based on covalent bonds whichgives rise to a very strong connection between the textile product andsheet, typically equalling prior art floor coverings that have to relyon physical embedding of the fabric and backing in an adhesive. Thecovalent binding of the molecules to the textile product and sheet cantake place by using any art-known method that enables reacting themolecules to the constituting yarns and fibres of the textile productand the sheet. Such method may for example rely on the samethermo-reversible bond which takes placed between the reactive moleculesthemselves.

In an embodiment wherein the textile product comprises polymer yarns, atleast part of the molecules are embedded in the yarns. Such embeddingcan for example be based on co-extrusion of the reactive molecules inthe polymer, but may also by based on molecular engineering, such asdevising a copolymer that has adequate properties to function as a yarnin a textile product, but has build-in blocks that are reactive (forexample a diene or dienophile when aiming at a Diels-Alder reaction).Another option for embedding is surface modification, for example bymolecularly attaching the required molecules (for example after glowingor otherwise preparing a surface for modification). Co-extrusion orother ways of spreading the reactive molecules throughout the polymer ofthe yarns (e.g. in a compounding process step that precedes actualextrusion) are preferred. This preference is not only based onsimplicity, but also meets the demand of enabling easy recycling: whenthe reactive molecules already form part of the polymer, the polymer canbe easy recycled while keeping the reactive molecules incorporated inits matrix.

In another embodiment, wherein the carrier sheet is formed from apolymer, at least part of the molecules are embedded in the sheet. Thisembodiment may comprise a sheet wherein the molecules are attached tothe surface of a sheet, or corresponding to the embodiment describedsupra, may for example be based on co-extrusion of the reactivemolecules in the polymer, or may be based on any form of molecularengineering. Also in this embodiment, co-extrusion or other ways ofspreading the reactive molecules throughout the polymer of the sheet arepreferred, for the same reasons.

In an embodiment wherein the self-supporting textile product comprisespolymer yarns, the polymer fibres are melted together at a side facingthe carrier sheet. Melting is an easy and reliable method to connectpolymer yarns to each other in order to provide the self-supportingproperties of the textile product. In a preferred embodiment, thepolymer fibres are polyamide fibres, preferably aliphatic polyamide suchas Nylon®.

In an embodiment the carrier sheet is in essence made from athermoplastic polymer, preferably polypropylene. Polypropylene is arelatively cheap material, easy to recycle and above all very suitableto produce a flexible, dimensionally stable sheet from.

In other embodiments, the covering is carpet, a carpet tile, a rug or amat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A 1C schematically show molecular models of various connectionsbetween a face fabric and carrier sheet.

FIG. 2 schematically shows the cross section of a floor coveringaccording to the invention.

FIG. 3 diagrammatically shows a process to manufacture a floor coveringaccording to FIG. 2.

FIG. 4 schematically shows a blade for melting yarns present in anintermediate product.

FIG. 5 shows a detail of the blade of FIG. 4.

FIG. 6 schematically shows the positioning of the blade according toFIG. 4 for producing a self-supporting textile product.

FIG. 7 shows a detail of the positioning of the blade according to FIG.6.

FIG. 8 depicts an alternative arrangement of the arrangement shown inFIG. 7.

FIGS. 9A-9D schematically show various arrangements with two heatedsurfaces.

Example 1 describes various fibre-binding experiments.

Example 2 describes various proof-of-principle experiments formanufacturing floor coverings.

Detailed Description

FIG. 1

In FIG. 1 some molecular models of various connections 5 between atextile product (1, 11, 21) and a carrier sheet (2, 12, 22) aredepicted. In FIG. 1A reactive molecules A, in this case comprising dienegroups, are integrated with the textile product 1, in this example bycovalent binding to the self-supporting textile product 1. Reactivemolecules B, in this case comprising dienophile groups, are covalentlyattached to carrier sheet 2. The molecules A and B have formed a thermoreversible Diels-Alder adduct.

In FIG. 1B another example is given wherein reactive molecules A and Bare used. In this example, reactive molecules B are compounded in thepolyamide polymer of which the yarns of textile product 11 areconstituted. The same way, reactive molecules A are compounded in thepolypropylene polymer of which sheet 12 is made. Both components areconnected through reaction between molecules A and B to form connection15. In FIG. 1C, reactive molecules B are coated on the back side oftextile product 21 and on the front side of sheet 22. The textileproduct and the sheet are sandwiched with an intermediate layer ofreactive molecules A in between. After the reaction between molecules Aand B has taken place, a connection 25 using the covalent interactionsbetween reacted molecules A and B is in place. In order to providesufficient integral bonding strength in the example of FIG. 1C, thesurfaces of the textile product 21 and sheet 22 are activated using aglow-discharge process.

FIG. 2

FIG. 2 schematically shows the cross section of a floor coveringaccording to the invention. This covering comprises carrier sheet 2 towhich is bonded textile product 1. This textile product is constitutedof polyamide primary backing 101 and polyamide yarns 100. The yarns andthe backing are melted together to form layer 102 that provides securemechanical locking of the yarns to the backing, this way providing aself-supporting textile product 1 (viz. a product wherein the fibres aremechanically interlocked as opposed to a backing wherein thefibres/yarns are simply applied without actually locking them, leadingto easy removability of the fibres/yarns upon a simple pulling force byhand). This self-supporting textile product is connected to sheet 2 byhaving bonds 5 (see FIG. 1A) in place.

FIG. 3

FIG. 3 diagrammatically shows a process to manufacture a floor coveringaccording to FIG. 2. The process is initially comprised of two separate(semi-)continues processes 200 and 300. Sub-process 200 is the processwherein the self-supporting textile product is made to be ready forconnection to a carrier sheet. Process 300 is the sub-process forpreparing the carrier sheet.

In step 201 tufting of polyamide yarns in a polyamide backing takesplace. The backing in this case is a continuous backing with a width ofapproximately 4 meters. The tufted fabric is transported to an operatingstation where the fibre (yarn) binding process 202 takes place. In thisembodiment a hot metal blade (knife) is transported under pressure overthe back side of the tufted fabric, which leads to the melting of theends of the polyamide yarns and part of the polyamide backing, and thusa stable interconnection between these yarns and the backing (thusleading to a self-supporting textile product). A further advantage ofthis yarn binding process is that the backside of the tufted fabricbecomes more flat, ultimately providing a good contact surface forconnecting the carrier sheet to the fabric. In a next step 203 (thefibre saving step) the self-supporting textile product is led understretch over a hot roller, such that the yarns are pushed into thedirection of the face side of the product. This process leads to ahigher pole, or when a predetermined standard pole is created, a savingof about 5-10% of yarn length. In the last step of sub-process 204 acompound comprising reactive molecules A is applied to the back side ofthe self-supporting textile product.

Parallel to sub-process 200, sub-process 300 is performed. In a firststep 301, a sheet is provided, in this case by unwinding a polymersheet, approximately 4.5 meters in width with a weight of 30 g/m², froma roll. In this embodiment, in step 302 the sheet is dimensioned bycutting the edges such that the sheet has the same width as the ultimateface fabric that comes out of process 204. In step 302 a compoundcomprising reactive molecules B is applied to the top surface of thesheet.

After this, the self-supporting textile product and the carrier sheetare brought together under circumstances wherein the molecules A and Breact to form covalent bonds (reacting step 400). In this embodiment,the resulting floor covering is dimensioned to form carpet tiles indimensioning step 401.

FIG. 4

FIG. 4 schematically shows a blade 30 for melting yarns present in anintermediate product. This blade basically consists of an aluminum bodywith a length of approximately 210 mm (suitable for providing a textileproduct with a width of 210 mm; in practice an operating width of up to4-6 meters is foreseen, typically obtained with multiple smaller lengthblades). The upper part 31 of the blade has a width of 25 mm. The lowerpart 32 converges to form a tip 33. Part 32 is coated with an anti-stickcoating, in this case a PTFE (polytetrafluoro-ethylene) coating. Theupper part is provided with internal heating elements 35 and 36, whichelements are available under the tradename FAK, from Ihne&Tesch GmbH,Nümberg, Germany. These elements have a capacity of 600 watt in totaland are able to evenly heat the blade up to about 450° C. Thetemperature is controlled using a Fe—CuNi temperature sensor (notshown). The blade can be vibrated in the direction A, i.e. in adirection parallel to the length of the blade. The typical vibrationfrequency is 7000 Hz, although higher frequencies, for example between30.000 and 40.000 Hz may provide better results with regard topreventing molten material to be deposited on the blade. The usedamplitude is between 1-5 μm, typically around 2-3 μm.

FIG. 5

FIG. 5 shows a detail of the blade of FIG. 4. In this figure the lowerpart 32 of the blade is shown, ending in tip 33. This tip has a radiusof 1 mm. Depending on the flexibility of the textile product, thisresults in a blade working surface of about 1 mm.

FIG. 6

FIG. 6 schematically shows the positioning of the blade 30 according toFIG. 4 for producing a self-supporting textile product. In thisarrangement, an intermediate product 1′ is guided along roller 40 and 41in the shown direction B (transverse to direction A as depicted in FIG.4) to reach heated blade 30. The tip 33 of the blade 30 is pressedagainst the back of the intermediate product 1′. This way the piles,i.e. at least their parts adjacent the back surface of the intermediateproduct 1′, are melted and the melted material is spread to becomesubstantially flat. Thereafter the product cools down therebymechanically binding the piles into the product to become textileproduct 1, which product is guided along rollers 42 and 43. The processof 1) at least partly melting the fibres of the piles, 2) spreading themolten material and 3) cooling down the molten material to below itssolidification temperature is a fibre binding process in the sense ofthe present invention.

FIG. 7

FIG. 7 shows a detail of the positioning of the blade according to FIG.6. As shown in FIG. 7, the blade 30 is positioned at a certain depthwith regard to the transport plane of product 1. This depth “d” isadjustable between 0 and 50 mm. By increasing the depth above 0, theblade is actually pressed against the back of the product (whichmechanically is the same as pressing the product against the blade). Thedepth needed depends on the melting and spreading result desired, thetemperature of the blade and the type of intermediate product (someproducts can withstand a higher pressure than others). As understood, ifan intermediate product can not withstand a very high depth, for exampleonly 3 mm, then with a certain temperature of the blade, the speed ofthe product can be adapted (lowered when the spreading result isinsufficient, increased when the intermediate product is molten to a toohigh degree). The other way around, at a certain transport speed andblade temperature, one can alter the depth “d” until a desired spreadingresult is obtained. If the product tears (given a too high pressure ofthe blade on the intermediate product) before a desired result isobtained, the transport speed can be lowered and/or the bladetemperature can be increased. Many more variations are within the reachof the skilled person.

FIG. 8

FIG. 8 depicts an alternative arrangement of the arrangement shown inFIG. 7. In this alternative arrangement the intermediate product 1′ isfed between blade 30 and a roller 45. This way the ultimate pressurewith which the blade is pressed against the back surface of theintermediate product can be increased, while at the same time decreasingthe risk of tearing of the product while subjected to the heat treatmentand pressure of the blade.

FIG. 9

FIG. 9, having the sub-FIGS. 9A, 9B, 9C and 9D schematically showsvarious arrangements with two heated surfaces. The FIGS. 9A, 9B and 9Cconcern arrangements with two heated blades. In such two-bladearrangements the first blade 30A can be used to effectively increase thetemperature of the intermediate product 1′ and optionally achieve apreliminary fibre binding result. The second blade 30B can be used toprovide the finishing fibre binding, that is the complete melting of theyarns as desired and spreading of the molten material to obtain asubstantially flat back surface, with the fibres being actuallymechanically locked into the textile product 1. In the arrangement shownin FIG. 9D, the first heated surface is a contact roller 46 which rollsin conjunction with the intermediate product 1′. In essence there is nospeed difference between the surface of roller 46 and the part of theback surface of product 1′ that is pressed against the roller. Theultimate fibre-binding takes place by the provision of blade 30, whichin this constitution exists of a flat blade with a working surface 33.The blade is connected to a semi-spherical body 50 which serves as aheat capacitor.

Example 1

Three intermediate products 1′ were made to be subjected to afibre-binding process according to the invention. These products aredescribed in Table 1. All three products were based on non woven primarybackings available from Freudenberg, Weinheim, Germany under thetradename Lutradur™, viz. Lutradur T6412 and Lutradur eco respectively.Two different types of yarns were used. The first yarn wasPA6/2600/240/RDD/du of Aquafil, Arco (TN), Italy, which yarn has anuncompressed yarns thickness of about 1 mm. The second one was a yarnmade from recycled PET, obtainable from Pharr Yarn, Mc Adenville, N.C.,USA, which yarn has an uncompressed yarn thickness of 1.3 mm. It isnoted that the latter yarn is indicated to be a “polyester” yarn by themanufacturer. The yarns were applied to the backings by forming loops atthe back of the backing material, while at the same time extendingthrough this backing to form piles at the front surface. Two cut pilesas well as one loop pile intermediate product were made as indicated inTable 1. The resulting intermediate products had thicknesses of 8, 6.5and 12 mm respectively.

TABLE 1 Intermediate products 1'A, 1'B and 1'C Intermediate product 1'1'A 1'B 1'C backing Lutradur T6412 Lutradur T6412 Lutradur eco polymerpolypropylene polypropylene polyester thickness backing 0.5 mm 0.5 mm0.5 mm weight backing ±115 g/m2 ±115 g/m2 ±115 g/m2 melt temperature295° C. 295° C. 295° C. backing yarn material PA6 PA6 PET height of the6 mm 5 mm 15 mm piles when stretched type of pile cut pile loop pile cutpile melt temperature yarns 250° C. 250° C. 280° C. weight product 870g/m2 750 g/m2 1.400 g/m2 (backing + yarns) thickness product 8 mm 6.5 mm12 mm

These three intermediate products 1′ were subjected to a fibre-bindingprocess using the arrangement of FIG. 4. The blade temperature was 300°C., the depth “d” of the blade was about 10 mm (such that theintermediate products were compressed to have a thickness at the bladeof about 2-3 mm in total) and the transport speed (direction B) was 0.2m/min. The vibrating frequency of the blade was 7 kHz, with an amplitudeof about 2 μm. With this set-up the yarns of the piles could bemechanically bonded into the textile product, while at the same time avery flat back surface was provided.

The resulting thicknesses of the self-supporting textile products was 5mm, 5 mm and 10 mm for the resulting self supporting products 1 A, 1 Band 1 C respectively (see Table 2), indicating that the textile productswere substantially flattened with respect to the intermediate products(without interfering with the pile heights). The reduction in thicknessby the fibre-binding process is mainly due to the spreading of the loopsof yarns at the back of the textile product. However, also part of thenon woven backing is believed to be molten, pressed together and spreadtogether with the molten yarn material (since none of the backingmaterial fibres could be removed by hand at the sides of the restingproducts). The resulting flat surface of the textile product enablesdirect application of any of the products on a floor or any otherarticle (such as the interior of a car or plane), or for example on aflexible, dimensionally stable sheet to form a carpet or carpet tile.

TABLE 2 Textile products 1A, 1B and 1C Textile product 1 1 A 1 B 1 Cthickness of the end product 5 mm   5 mm 10 mm thickness reduction dueto fibre binding 3 mm 1.5 mm  2 mm

In this example the polymer materials used for the yarns and backing arepolyamide 6, polyester, polypropylene and polyethylene terephthalate,but other materials may also be used, depending on the desiredproperties of the textile product. Other suitable polymer materials arefor example other types of polyamide (PA 6.6), polyethyltrimethylene,biodegradable polymers based on lactic acid etc.

It is noted that to reach a transport speed of 20 m/min or higher, it isestimated that the blade should have a temperature of between 600-700°C., depending mainly on the type of backing (in particular woven ornon-woven), the materials used for the pile yarns as well as thebacking, and the desired flatness of the back side of the textileproduct. For such high temperatures a suitable non-stick coating wouldfor example be a silicon oxide hybrid sol-gel coating as offered bySchaepman, Kampen, The Netherlands.

Example 2

In a first experiment the principle is shown that a self-supportingtextile product can be thermo reversibly bound to a dimensionally stablecarrier material using a diene and dienophile as reactive molecules,leading to thermo reversible covalent interactions. For this, acommercially available maleimide coated glass slide (Xenopore, MSP 00010; available from Xenopore, Hawthorne, N.J., USA) was used. The textileproduct was a fabric of polyamide fibres tufted in a polypropylene wovenfabric. The fabric was made self-supporting by melting the backside witha little flame, sufficient to fixate the individual filaments in theiryarn. The additional reactive molecules were comprised in a mixture ofbutyl-methacrylate (85 molecular percent) and furfuryl-methacrylate (15molecular percent).

This mixture was spread out over the glass slide (0.44 grams on a slideweighing 4.66 gram; which is believed to be an excess of reactivemixture) and warmed in an oven at 175° C. for 2 minutes. After meltingand spreading of the mixture over the slide, the self-supporting fabric(2.27 grams) was brought in contact with the glass slide and kept in theoven at 175° C. for 2 minutes with a pre warmed weight (1 kg) on top ofit to ensure good interaction between the glass slide and the fabric.After 5 minutes, the slide was cooled down to room temperature and theconnection between the carrier and the self-supporting fabric wasevaluated. A firm connection of tufted fabric and glass slide wasobserved. It appeared to be impossible to remove the tufted fabric fromthe glass slide by manual forces. Attempts to pull out individualpolyamide fibres from the face fabric also failed.

To show thermo reversibility of the connection, the construction wasreturned to the oven at temperature of 175° C. and warmed for 3 minutes.After this, the self-supporting fabric could be easily removed from theglass slide. The procedure of connection/disconnection of the fabric tothe carrier was successfully repeated two times, which shows the thermoreversibility of the chemical bonding system.

In a second experiment other reactive molecules were used, viz. 85molecular percent butyl-acrylate, 3 molecular percent acrylic acid and12 molecular percent furfuryl methacrylate; to this composition astoichiometric amount of 4,4-bis(maleinimido)diphenylmethane was addedfor internal polymer cross linking in competition with the connection tothe carrier slide. The rest of the experimental set up was identical tothe first experiment (although the fabric weighed slightly less, 1.91grams). The thermo reversible connection was the same as observed in thefirst experiment.

The invention claimed is:
 1. A method for manufacturing a carpetcomprising the steps of: providing an intermediate product comprising abacking including a thermoplastic material and having a front surfaceand a back surface, and yarns applied into the backing, the yarnsextending from the front surface of the backing material, feeding theintermediate product along a body having a heated surface, the backsurface being pressed against the heated surface, to at least partlymelt the yarns present in the intermediate product to form the carpetsuch that the thermoplastic material of the backing co-melts with theyarns, providing a relative speed of the part of the back surface thatis pressed against the heated surface with respect to the heatedsurface.
 2. A method according to claim 1, wherein the heated surface isan edge of a blade.
 3. A method according to claim 2, wherein the stepof feeding includes a step of feeding the intermediate product betweenthe blade and a rotating drum facing the blade.
 4. A method according toclaim 2, further including a step of vibrating the blade when pressedagainst the back surface.
 5. A method according to claim 2, furthercomprising a step of thermally connecting the blade to a non-flatcarrying element.
 6. A method according to claim 1, further comprising astep of preheating the back surface before being pressed against theheated surface of the body.
 7. A method according to claim 6, whereinthe step of preheating includes a step of preheating the back surface bypressing a heated preheat surface against the back surface, the preheatsurface being one of: a preheat drum and a preheat blade.
 8. A methodaccording to claim 1, wherein the yarns extend through the backing, andfurther comprising a step of melting at least a part of the yarns thatextends out of the back surface.
 9. A method according to claim 8,further comprising a step of at least partially melting a part of theyarns applied into the backing.
 10. A method according to claim 1,Wherein the backing is a non woven fibrous material.